How Water Infrastructure Shaped LA

California and its landscape were shaped by water in more ways than one. Water infrastructure projects in the early 20th century were an important part of helping Los Angeles grow and expand its population to become one of the largest cities in the world.

William Mulholland's St. Francis Dam helped create the reservoir to supply water to the growing city of Los Angeles in the early 20th century.

In his video presentation, British entertainer Tom Scott recounts this time in California history and the impact such water infrastructure projects had on the region—particularly the collapse of the St. Francis Dam.

Bringing Water to the City

Scott calls out William Mulholland as one of the reasons Los Angeles is the shape and size it is today.

While superintendent of the Los Angeles Water Company, Mulholland was responsible for the construction of the Los Angeles Aqueduct. Completed in 1913, the aqueduct carried water 233 miles from the Owens Valley to a storage reservoir (dammed by the St. Francis) and on to Los Angeles.

The construction and failure of the St. Francis Dam helped contribute to the city of Los Angeles we see today, Tom Scott says.

Although it delivered the water resources the city needed to flourish, this supply was at the expense of the valley’s agricultural farmlands. As those farms went dry, the farmers and landowners set to trying to sabotage the aqueduct infrastructure with dynamite, leading to what became known as the California Water Wars.

But it wasn’t dynamite that led to the collapse of the St. Francis Dam.

While cracks were not unexpected in the curved concrete gravity dam at the time, the appearance of more cracks and evidence of leakage led Mulholland and his chief engineer to perform an inspection. Although they determined the structure needed maintenance, they didn’t think the situation was urgent.

Just 12 hours later, the dam collapsed in what was deemed the worst U.S. civil engineering disaster of the 20th century. The rushing waters followed the riverbed through the canyon and neighboring towns—destroying businesses, 1,200 homes and hundreds of lives—carrying debris and remains across 54 miles of land to the Pacific Ocean.

The dam failure was contributed to its construction on ground that was not solid bedrock and which was further softened by water seepage.

Although the cause of the failure was determined to be an engineering fault related to the stability of the geology of the area, Mulholland’s career was effectively over and he retired the following year.

As a result, state of California determined that the design of construction projects needed more regulation or else the public would be put at risk. In 1929, the California legislature passed laws to regulate civil engineering and created the state Board of Registration for Civil Engineers (now the Board for Professional Engineers, Land Surveyors, and Geologists).